Identification, quantification and analysis of observable anthropogenic debris along swiss river and lakes (IQASL)¶
IQAASL is a project sponsored by the Swiss Federal Office for the Environment to quantify shoreline trash along swiss lakes and rivers. Multiple small scale litter surveys are completed at different locations within a designated survey area. For the year 2020/2021 the survey areas were defined by the municipalities that border the Aare, Rhône, Ticino and Linth/Limmat rivers and any lakes or rivers that contribute to one of these rivers.
What is a litter survey?¶
A litter survey is the identification and count of all anthropogenic objects found within a delimited area, in this study all surveys were bordered on one side by water (a river or lake). Each object is placed into one of 260 categories¹. The location, date, survey dimensions and the total number of objects in each category is noted.
Purpose of the surveys¶
The survey results help ALL stakeholders identify the items that make up the mass of trash found in the natural environment and where those objects are most likely to be found. The surveys answer the following questions:
- What items are found?
- The most abundant objects from the water feature and the survey area sorted by total object count
- How much is found ? (total weights and item counts)
- Total object count, total weight and weight of plastics
- How often are these items found?
- How often the most abundant items were identified
- Where do you find the most?
- Pieces of trash per meter (pcs/m): the ratio of number of objects found to the length of the shoreline for each survey location
These are the most frequently asked questions and should be considered when determining any mitigation or reduction strategies.
Assumptions:¶
- The more trash there is on the ground the more a person is likely to find
- The survey results represent the minimum amount of trash at that site²
- For each survey: finding one item does not effect the chance of finding another³
Purpose of this report¶
Summarize the results for the water feature and define the magnitude of those results with respect to the rest of the survey area.
Contents of this report¶
Scope: description of water feature
- survey locations
- lakes and rivers
- municipalities and effected population
Survey dimensions: locations, aggregated totals
- weights and measures: cumulative
- weights and measures: cumulative by survey location
- survey totals by location: pcs/m by date
- material type: % of total
Trash removed: the most abundant objects
- the most common objects from the survey area
- the most common objects from all the survey areas
- pcs/m of the most common objects for all water features
Trash removed: the most frequent
- The rate at which the most frequent objects were identified
- utility classification: % total of all objects found
- effective data: report of missing records
- correlation of results to local conditions
- survey location coordinates
- itemized list of objects removed
More information¶
For more information about the project visit project home.
If you would like more information about this survey area please contact:
- Swiss federal office for the environment - Municipal waste section
- analyst@hammerdirt.ch
¹ The EU guide on monitoring marine litter
² There is most likely more trash at the survey site, but certainly not less than what was recorded.
³ Independent observations : stats stackexchange
Scope¶
The Aare source is the Aare Glaciers in the Bernese Alps of south-central Switzerland. The Aare is the longest river entirely within Switzerland with a length of 295 km and drainage area of 17,779 km2. Following the Aare Gorge, the river expands into the glacial Lake Brienz. The Aare is canalized at Interlaken before entering Lake Thun and exiting through the city of Thun.⁵ The river then flows northwest surrounding the old city center of Bern on three sides. Continuing west to Lake Wohlen Reservoir it turns north to Aarberg and is diverted west into Lake Biel by the Hagneck Canal, one of a series of major water corrections made in the 19th and 20th centuries connecting Neuchatel, Biel and Morat lakes through canalization. From the upper end of Lake Biel, at Nidau, the river exits through the Nidau-Büren Canal/Aare Canal.⁶
The Limmat and Reuss rivers⁷, two major tributaries converge into the Aare at the Limmatspitz between the cities of Brugg and Untersiggenthal in Canton Aargau.⁸ The Aare river ends in the north-western region of Koblenz, Switzerland where it joins the Rhine river which eventually terminates in the North Sea.
⁵ The Editors of Encyclopaedia Britannica. (1998, July 20). Aare River. Retrieved from Britannica.com: https://www.britannica.com/place/Aare-River
⁶ Standard Encyclopedia of Worlds Rivers and Lakes. (1965) R.K. Gresswell
⁷ The Limmat and Reuss are part of different survey areas
⁸ Pro Natura . (n.d.). Limmatspitz. Retrieved from Pro Natura : https://www.pronatura-ag.ch/de/Gebenstorf-limmatspitz
Survey locations, municipalities¶
Cumulative totals by water feature¶
Survey totals pieces per meter, material type % of total¶
The most abundant objects: results by water feature¶
Some objects are found throughout the survey area and some of those objects are found in all survey areas. Knowing which objects are most abundant and what those values are helps idenitify sources or zones of accumulation.
How often are these objects found?¶
Some objects are found often and in elevated quantities, others are found often and in small quantities and some objects are found less often but in large quantities. Knowing the diffference can help find the sources.
The number of surveys where at least one of the most abundant objects were found¶
Note The survey area results include the results from the current water feature
Utility: percent of total objects collected¶
The utility type is based on the utilisation of the object prior to it being discarded. Objects that are found are placed into to one of the 260 categories. Those categories are grouped according to utilisation.
For example, a piece of plastic could be placed into the category 'Fragmented plastics', depending on its size. However, a piece of plastic that was once a bucket and we know this because we are familiar with either the brand or the product or if we recognize it as a piece of a bucket it is placed in the code for buckets⁸.
- wastewater: items released from water treatment plants includes items likely toilet flushed
- micro plastics (< 5mm): fragmented plastic items and pre-production plastic resins
- infrastructure: items related to construction and maintenance of all infratructure items
- food and drink: primarily single use plastic items related to consuming food and drinks outdoors
- agriculture: primarily industrial sheeting includes mulch films
- tobacco: primarily cigarette ends includes all smoking related material
- recreation: includes fishing, hunting, boating and beach related objects, excludes food, drink and tobacco items
- packaging non food and drink: packaging or wrapping material not identified as food, drink nor tobacco related
- plastic fragments: foam and plastic fragments of indeterminate origin and use
- personal items: accessories, hygiene and clothing related
⁸ See the annex for the complete list of objects identified, includes category and group classification - the code for a buckets is G57
More information¶
Contact hammerdirt.ch for any questions about the content of this report. If you would like a report for your municipality contact the Swiss federal office for the environment: Municipal waste section.
Correlation of results to local conditions¶
The survey results for the most abundant objects were ranked against population and three other criteria for each survey location. Within a radius of 1500m of each survey location the following characteristics were calculated:
buildings: m² of surface area attributed to buildings
streets: length in meters of all roads
number of stream/river discharge points
The three attributes were evaluated seperately and combined - urbanization. Urbanization is the weighted value of the sum of population, buildings and streets for each survey. The values were evaluated using the Spearmans rank correlation with p= 0.1. The results can be interpreted in the following way:
" + " - positive correlation: the chances of finding the object and the quantity found were increased as the amount of the attrubute increased within 1500m the survey area.
" - " - negative correlation: neither the chances or the quantity of finding the object found were increased by this attribute, and previously it was found in greater quantities when this atribute was minimized within 1500m of the survey area.
" NA " - no effect: there is no statistical basis to reject a null effect by this attribute based on the current results.
Important! Results vary for each location and at each survey. A correlation is not a sign of causation.
